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101.
Justin Solomon Mirela Ben‐Chen Adrian Butscher Leonidas Guibas 《Computer Graphics Forum》2011,30(2):365-374
The discovery of meaningful parts of a shape is required for many geometry processing applications, such as parameterization, shape correspondence, and animation. It is natural to consider primitives such as spheres, cylinders and cones as the building blocks of shapes, and thus to discover parts by fitting such primitives to a given surface. This approach, however, will break down if primitive parts have undergone almost‐isometric deformations, as is the case, for example, for articulated human models. We suggest that parts can be discovered instead by finding intrinsic primitives, which we define as parts that posses an approximate intrinsic symmetry. We employ the recently‐developed method of computing discrete approximate Killing vector fields (AKVFs) to discover intrinsic primitives by investigating the relationship between the AKVFs of a composite object and the AKVFs of its parts. We show how to leverage this relationship with a standard clustering method to extract k intrinsic primitives and remaining asymmetric parts of a shape for a given k. We demonstrate the value of this approach for identifying the prominent symmetry generators of the parts of a given shape. Additionally, we show how our method can be modified slightly to segment an entire surface without marking asymmetric connecting regions and compare this approach to state‐of‐the‐art methods using the Princeton Segmentation Benchmark. 相似文献
102.
Justin Solomon Mirela Ben‐Chen Adrian Butscher Leonidas Guibas 《Computer Graphics Forum》2011,30(5):1543-1552
Cartoon animation, image warping, and several other tasks in two‐dimensional computer graphics reduce to the formulation of a reasonable model for planar deformation. A deformation is a map from a given shape to a new one, and its quality is determined by the type of distortion it introduces. In many applications, a desirable map is as isometric as possible. Finding such deformations, however, is a nonlinear problem, and most of the existing solutions approach it by minimizing a nonlinear energy. Such methods are not guaranteed to converge to a global optimum and often suffer from robustness issues. We propose a new approach based on approximate Killing vector fields (AKVFs), first introduced in shape processing. AKVFs generate near‐isometric deformations, which can be motivated as direction fields minimizing an “as‐rigid‐as‐possible” (ARAP) energy to first order. We first solve for an AKVF on the domain given user constraints via a linear optimization problem and then use this AKVF as the initial velocity field of the deformation. In this way, we transfer the inherent nonlinearity of the deformation problem to finding trajectories for each point of the domain having the given initial velocities. We show that a specific class of trajectories — the set of logarithmic spirals — is especially suited for this task both in practice and through its relationship to linear holomorphic vector fields. We demonstrate the effectiveness of our method for planar deformation by comparing it with existing state‐of‐the‐art deformation methods. 相似文献
103.
Lennart Åqvist (1992) proposed a logical theory of legal evidence, based on the Bolding-Ekelöf of degrees of evidential strength. This paper reformulates Åqvist's model in terms of the probabilistic version of the kappa calculus. Proving its acceptability in the legal context is beyond the present scope, but the epistemological debate about Bayesian Law isclearly relevant. While the present model is a possible link to that lineof inquiry, we offer some considerations about the broader picture of thepotential of AI & Law in the evidentiary context. Whereas probabilisticreasoning is well-researched in AI, calculations about the threshold ofpersuasion in litigation, whatever their value, are just the tip of theiceberg. The bulk of the modeling desiderata is arguably elsewhere, if one isto ideally make the most of AI's distinctive contribution as envisaged forlegal evidence research. 相似文献
104.
Using selected incubation conditions we have identified intermediate steps, between the first glucose transferred to protein and the appropriate substrate for glycogen synthase. Mn2+ stimulates the addition of the first, and probably, the second glucose molecule to the acceptor protein but inhibits further elongation. In the presence of Mn2+ only one radioglucosylated protein band of M(r) 42 kDa was evident. In the absence of Mn2+, two bands of 60.7 and 64.6 kDa were obtained indicating elongation of the glucan chains. After Glc6P addition a family of glucosylated proteins with higher M(r) was obtained, as reported previously. Mn2+ inhibition of the second step, is reversed by PMSF+Glc6P addition. Under these conditions a family of radioglucosylated protein bands with M(r) far in excess of 42 kDa, similar to that obtained without Mn2+, was obtained. Therefore, two different transglucosylating activities were necessary, at least, to prepare the appropriate substrate for glycogen synthase. Based on these observations the model we proposed earlier for glycogen biogenesis is modified. The original "Glycogen Initiator" implies at present two enzymatic activities, Glycogen Initiator 1 (activated by Mn2+) and Glycogen Initiator 2 (inhibited by Mn2+). 相似文献
105.
106.
We recorded clinical information over a 12-month period on consecutive consultations to the gastroenterology service of the Durham VA Medical Center. Of 902 consultations, 789 were prospectively collected. Eighty-five percent of the patients were between 40 and 70 years old. Seventy-five percent of the referrals were from the internal medicine service. The most frequent reasons for consultation were abdominal pain (19%), GI bleeding (active, 16%; occult, 9%), abnormal results of liver tests (18%), and request for a procedure (11%). Diseases of the liver (32%) and "peptic diseases" (30%) were the most common diagnoses. One or more procedures were done in 71% of consultations. When these data are compared with those of a practicing gastroenterologist, using an identical instrument, it is apparent that trainees' experience with structurally identifiable gastroenterologic disease and with a variety of procedures was similar in scope. There were, however, differences in that the physicians at the VA saw substantially fewer patients with so-called "functional" illness. If these data are applicable to other VA Medical Centers, then the training of physicians in gastroenterology at a VA Medical Center should probably be broadened. 相似文献
107.
A combined diagnosis of maturity is described, which is harmless in a correct technique. The method can be carried out in each of obstetrical hospital together with a routine laboratory. By means of the combined diagnosis a "maturity-index" is performed, which permits a certain assessment of the survival-chance of the praemature delivered children. In connection with the ultrasound-cephalometrie also there is an exact evidence to the duration of pregnancy and the tendence of intrauterine growth of the fetus. 相似文献
108.
M. V. Fischetti S. E. Laux P. M. Solomon A. Kumar 《Journal of Computational Electronics》2004,3(3-4):287-293
We review briefly some aspects of the history of Monte Carlo simulations of electronic transport in semiconductors. In the early days their heavy computational cost rendered them suitable only to study problems of pure physics, as simpler models provided the answers necessary to design ‘electrostatically good’ devices. Now that scaling has taken another meaning (i.e., looking for alternative materials, crystal orientations, device geometries, etc.), Monte Carlo simulations may gain popularity once more, since they allow an efficient and reliable evaluation of speculative ideas. We show examples of both aspects of the results of Monte Carlo work. 相似文献
109.
Budson Andrew E.; Simons Jon S.; Sullivan Alison L.; Beier Jonathan S.; Solomon Paul R.; Scinto Leonard F.; Daffner Kirk R.; Schacter Daniel L. 《Canadian Metallurgical Quarterly》2004,18(2):315
National traumatic events can produce extremely vivid memories. Using a questionnaire administered during telephone interviews, the authors investigated emotional responses to, and memory for. the September 11, 2001, terrorist attacks in patients with Alzheimer's disease (AD), patients with mild cognitive impairment (MCI), and healthy older adults in the initial weeks following the event and again 3-4 months later. There were several notable findings. First, patients with AD showed less memory than patients with MCI and older adults. Second, patients with AD, but not patients with MCI or older adults, appeared to retain more memory for personal versus factual information. Third, patients with AD and older adults did not differ in the intensity of their reported emotional responses to the attacks, whereas patients with MCI reported relatively less intense emotional responses. Last, distortions of memory for personal information were frequent for all participants but were more common in patients with AD. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
110.
Solomon Russom Habtay 《Creativity & Innovation Management》2012,21(3):290-303
Using the business model concept as a theoretical framework, this paper examines the relative disruptiveness potential between technology‐driven and market‐driven innovations. The study analyses retrospectively four case studies comprising two technologically sophisticated IT innovations and two technologically less sophisticated market‐driven innovations starting from their inception to the point of disruption over a period of 5–15 years. It finds that, while the disruption process of technology‐driven innovation conforms to the patterns predicted by disruptive innovation theory, the disruption process of market‐driven disruptive business model innovation depicts a bottleneck shape, where the positive effects of initial strategic choice, model specialization and investments on disruptiveness potential reach the maximum level and start to stagnate due to the same initial strategic choice and cost factors. Implications for researchers and practitioners are discussed. 相似文献